Preparation of 4-ketooctanedioic acids by hydrogenating certain dilactones with a palladium catalyst



United States Patent gangsta V PREPARATION or 4-KETO0CTANEDIOIC ACIDS BYHYDROGENATING CERTAIN DILACTONES WITH A PALLADIUM CATALYST 4 8 Claims.(onto-43731 This invention relates to anew method for preparing ketoacids containing a long chain. More particularly this invention relatesto a novel catalytic hydrogenation process for converting certaindilactones into long chain keto dicarboxyl'ic acids. l 1 v Octanedioicacid is produced when the dilactone obtained by reacting acetylene withcarbon monoxide over a cobalt carbonyl catalyst, as disclosed and'claimed in the copending application of J.. C. Sauer, Ser. N 549,155filed November 25, 1955, is treated with hydrogen in the presence ofplatinum in acetic acid. When the hydrogenation is effected withpalladium in a neutral medium, the product is tetrahydro [2,2-bifuranl-5,5'(2H,2H)dione.

It is an object of this invention to provide a new method for preparinglong chainketo dibasic acids. A further object is to provide a novelcatalytic hydrogenapressure drop, the reactor is "opened, excesshydrogen vented to the atmosphere, and the contents discharged V .M. W.,188.1 Found: C, 51.06; H, 6.43; N. E., 9 8. 6,'

tion process for converting certain dilactones into long chain ket'odicarboxylic acids. An important object is to provide a new and improvedprocess for preparing 4- ketooctanedioic acids. Another object is toprovide a new method for preparing 4-ketooctanedio'ic acids in twosteps, starting with abundantly available, low cost carbon monoxide andacetylenic compounds, such as acetylene. Other objects will appearhereinafter.

These and other objects of this invention are accomplished by thefollowing process for preparing 4-ketooctanedioic acids which comprisesreacting hydrogen and a dilactone havingin its ultraviolet spectrum astrong absorption'line in the region 3300 to 4400A and of the generalformula C (RR') O in which R and R" are hydrogen, haloaryl, alkoxaryl ormonovalent hydro carbon radicals free from non-aromatic unsaturationin*-- a medium having a pH less than 2 and in the presence of apalladium catalyst.

ated with palladium in the presence of a strong acid having a pH lessthan 2 the product is 4-ketooct'anedioic acid, i. e., 4-ketosubericacid. The dilactones employed in the process of this invention. areobtained by reacting an acetylenic compound, such as acetylene, withcarbon monoxide over a cobalt carbonyl catalyst as disclosed and claimedin said copending patent application of J. C. Sauer, Ser. No. 549,155.

In a convenient way of carrying out the process of this invention, apressure reactor is charged with dilactone, e. g., [A-bifuran]-5,5'-dione, acetic acid, and at least 1%, based on the weightof'dilacton'e, of a palladium catalyst. To this mixture there is addedenough concentrated hydrochloric acid to reduce the pH to below 2 andhydrogen is'then'intro duced at room temperature in amount sufficient toprovide at least '5 mole equivalents per mole of dilactone. Thetemperature of the system is maintained between 20 and 40 C. Afterreaction is complete, as evidenced by cessation of and filtered. Thefiltrate is thenva'cuum-distilled or evaporated to remove the acetic'and hydrochloric acids. The solid residue is recrystallizedfrom waterto yield almost pure 4-ketooctanedioic acid.

The examples which followare submitted to illustrate and not to limitthis invention.

Example I A slurry of 25 g.,. of the dilactone, [A bituran]-5,5-dione,prepared as described subsequently, with 4 ml. of concentratedhydrochloric acid and 2.5 g. of 10% palladium-on-charcoal catalyst in200 ml. of glacial, acetic acid was reduced in a Parr hydrogenationflask at room temperature. The system absorbed the theoretical-amount ofhydrogen. When the solvent was distilled from the filtered reactionproduct, the residual material crystallized upon cooling. -Thismaterialjwas then recrystallized from chloroform to yield '10 g. 'of' a.solid compound melting at 128-130? C. The compound after threerecrystallizations fromfwa'ter melted at -137.C. It was acidic to sodiumbicarbonate solution.

Analysis.Calcd. for CSHIZOE: C, 51.05;JH,'.6.43;

98.3. v Infrared analysisi 3.4,u..(saturated C-H), 5.85;; (ketonecarbonyl), 10.9 1. (carboxylic acid).

A semicarbazone was obtained from the 4-ketooc tanedioic .acid (0.90g.), described above, semicarbazide" hydrochloride (0.54 g.), sodiumacetate (0.75. g.), and water (10 ml.). The solid weighed 0.91 g;andjmelted at 146? C.,' after two recrystallizationstromlethanol.,

'Analysis.Calcd. for C H O N C, 44.07; H, 6.30; N, 17.14. Found: C,43.82; H,j6.35; N, 17.02, 17.10.

, Examp lc ll I v V The dilactone of Example I (25 g. acetic ac id (270ml.), concentrated hydrochloric acid (30 ml.) ,'and 10%palladium-on-carbon catalyst (1.6 g.) was shaken with hydrogen at roomtemperature at a maximum pressure of 45 lb./ sq. in. until absorptionceased. The product was filtered and evaporated to dryness to give asolid acid,

, 13.4 g. in crystalline form and an additional 7.3 g. as a tackysolid;total yield 72%. from ethylfacetate, chloroform, ,or water the 4-keto-After recrystallization octanedioic acid melted at 132-133 C. and didnotdepress the melting point of the sample described in Example I.

The unsaturated dilactone [A -bifuran]-5,5'- dioneused in the exampleswas prepared ;by. charging into a steel pressure reactor of 400 cc.capacity 26 g. of acctylene', 200 ml. of acetone, and 1.5 g. or jdicobalt o'cta} carbonyl. The mixture was heated with carbon monoxide at apressure of 1000 atmospheres for 14 to 17 hours. The product wasfiltered and the brown solid was extracte'd with. ethyl acetate for24.hours. The extract was permittedto crystallize and the crystallinematerial was separated, and dried at room temperature. .There was"obtained 20 g. of the unsaturated dilactone, C l-1 04, M. P. 229 (latterseveral recrystallizations from acetic.

acid.

The [A -bifuranl-5,5' dione exists inthe form 5 of two structuralisomers, which yield octanedioic acid a.

(suberic acid) when hydrogenated with platinum in Patented June 24, 1958C. is the cis form. The formulae of these structural isomers of [A--bifuran]-5,5-dione are as follows:

Home]:

Low melting or trans form 0 0:0 o=oo=o no=' ''hn Hi: JH

High melting or cls form These structural isomers of in -bifruanl-5,5'dione canbe represented by the structural formula Bothof thesestructuralisomers yield 4-ketooctahe'dioic acid by the proces ofthisinvention.

Although the hydrogenation or the [A -bifuranl-SJT-dione to"4-ketooctanedioic acidlhas been .effected batchwise, it is to be,understoodftliat; this is only, for convenience, and that it canbec'arried outas' a contim d; or semi-continuous up-flow,down-fiow,'co-current,

recovery of unconverted reactants for recycling.

tions.

4 The filter cake, after removal of most of the water, is dried in airand stored in a desiccator over calcium chloride. The catalyst, whichweighs from 40 to 50 g. and contains about 10% palladium, is stored,after being powdered, in a tightly closed container.

The pH of the medium in which the hydrogenation is effected is-cr-itical.- Thus, in acetic acid alone which has a pH" of 2.4 theproduct of the hydrogenation is 1,8- octanedioic acid. Addition of astrong acid such as hydrochloric acid,.to.; reduce the pH to below 2causes the reaction to. takea. different course and the product is a4*ketooctanedioic acid. Hydrochloric acid is the preferred acid becauseit is low in cost and because it seems to have an activating effect onthe palladium catalyst. It.,is.to be understood, however, that otherstrong acids such as sulfuric; hydrobromic, etc., can be used in placeof hydrochloric but they offer no advantage over hydrochloric and areless'preferre'd.

or couritercurrent vapor or liquidv phase operation, 'with I The processof this invention is generally applicable to any of the dilactonesobtained by reacting an acetylene with carbon monoxide in the presenceof a cobalt carbonyl catalyst, as disclosed and claimed in the copendingapplication of]; C. Sauer, U; S. Ser. No.549,l55, filed November 25,1955.

The cobaltcarb'onyl may be made directly by reaction of carbonmonoxidewith' the metal in active form as described in I. Am. Chem. Soc.70, 383-6 (1948).

The acetylenes used in preparing these dilactones correspond to RCEC-R',in which R and R are hydrogen, alkoxyaryl, especially where the alkoxygroup is of not more than .12 carbon atoms and the aryl radical ishydrocarbon of no more than 10 carbon atoms; haloaryl,

" especially chloroaryl where the aryl radical is hydrocarat. 20 C..However, higher temperatures up to 40 C.

can be used but since no practical advantages accrue from the use oftemperatures above 20 C. the range of20-25 C. embraces thetemperaturecouditions generally used.

The amount of catalyst is at least 0.10% by weight psenatiqn mnr edby nce insthe cataly p tafiwzrusua y. n m u t n y s hic s.

bifuranl-SJf-dione Jbeing,v hydrogenated.

Any active palladium. catalyst can be used. Thus, there can be usedPalladium orfany of its compounds,

e. g the onidepchlor'ide, nitrate, etc.,'and the catalyst can I beunsupported or supported. on inert, base 'rna'terialsL size of thesupport can vary from 40-300 mesh for use'influidized systems,-whereas--foruse in fixed bed systems supports qfzlargertparticlersize, e.g-.,.4-40 mesh -are-satis factory. f

Aauitableipalladiuni catalyst is prepared. by depositing. A

P l dium. chloridwm granular.ia iv t a nw 31 i m nt s sntttqeivea ontrationt t.0.2m

.1 of P lad um, Pe ter of tal s P er b e charcoal. issubjected totreatment with an acid suchBas nitric acid, prism contacting it wannapalladium compound. typical preparation the following:

A solution of 1 8 3 is prepared by heatingthe' mixture on a steam bath.The,

I v 3"g.*0fpalladiuirichloride inSQS rnlI of'concentratedhydrochloricacid and 40 ml. of water resulting solution is poured into a solution ofg. of-

, sodiumacetate-trihydrate in 500ml. of water contained in a--oneliterreduction bottlei Forty-five-grams of activated coconutcharcoalzisiaddedand the. mixture is hydro genateduntilhydrogentabsorption. ceases, whichwis be-, tween l and Zhoure,Thecatalyst is coll ected; on. a suction filter and worked with 2 litersof water in five porbon of not more than 10 carbon atoms, or monovalenthydrocarbon radicals, free from non-aromatic unsaturation, especially ofnot more than 12 carbon atoms, e. g.,

alkyl, especially short chain alkyl, i. e., containing not more than 7carbon atoms, aryl, especially where the aryl radical is hydrocarbon ofnot more than 10 carbon atoms, dialkyl, especially of not more than 7carbon atoms, or cycloalkyl, particularly of not more than 7 carbonatoms. Examples of such radicals are methyl, ethyl, octyl, decyl,dodecyl, phenyl, tolyl, xylyl, naphthyl, benzoyl, cyclohexyl, methylcyclohexyl,chlorophenyl, methoxyphenyl, ethoxyphenyl, decylphenyl,dodecyloxyphenyl, dodecyloxynaphthyl, andthe like. Examples of suchacetylenes areacetylene, methylacetylene, Z-decyne, phenylacetylene,naphthylacetylene, p-chlorophenylacetylene, p-ethoxyphenylacetylene,p-decyloxyphenylacetylene, benzylacetylene, ,cy clohexylacetylene,methylcyclohexylacetylene, and.

the like.

By. employing such substituted acetylenes there are obtained dilactonescorresponding in molecular formula to C (RR') O;, theradicals R and Rcorresponding to the; substituents attached to the triply bonded carbonin the acetylenereactant, i. e., Rand R in RCEC-R'. Thus, asshown by theaforementioned Sauer application thereare prepared the followingdilactones:

and the like.

The reaction between the acetylene and carbon monoxide is carried' outbatchwise or continuously in the presenceofaninertorganic liquid medium.By inert organic liquidrnedium. is meant organic liquids which containno active hydrog'en,- as defined by S. Siggia in his QuantitativeOrganic; Analysis Via Functional Groups, 2nd ed. '(1954), pz. 78,chapter. 7, and as determined by the Zerewitinofi, method, Ber. 40, 2026(1907); I. Am. Chem. Soc. 39, 3181 (1927). Thus, the acetylene is theonly compound in the reaction system which may contain active hydrogen.Specific organic reaction media are isooctane, toluene, acetonitrile,acetone, ethyl acetate, dioxane, cyclohexanone, xylene, benzene, and thelike.

The unsaturated dilactones can be represented by the general formulawhere one of the ring doubly bonded carbon atoms has its free valencesatisfied by R and the other of the ring doubly bonded carbon atoms hasits free valence satisfied by R, with R and R being defined as aforesaidwith respect to the acetylenic reactants. These unsaturated dilactonesexist in two isomeric forms which can be represented by the generalformulae:

and

Trans form EXAMPLE A A reactor was charged with 0.49 g. of4-ketooctanedioic acid and 0.30 g. of hexamethylenediarnine, evacuated,and sealed. The reaction mixture was then heated for one hour at 200 C.,the reactor allowed to cool, and opened. There was obtained atranslucent, pliable polymer which was useful as a coating material forrigid and flexible substrates. The polymer was insoluble in such organicsolvents as acetone and dimethylformamide.

EXAMPLE B A reactor was charged with 0.25 g. of 4-ketooctanedioic acidand 0.14 g. of 1,4-butanediol, evacuated, and sealed. The reactionmixture was heated for one hour at 200 C., the reactor was opened, andthe heating continued at 235 to 240 C. for 1.5 hours longer. The reactorwas allowed to cool and the contents removed. The product was a tackypolymer useful as an adhesive. It had a molecular weight of 720, 730 andwas soluble in acetone.

Since these compositions contain the oxo group originally present in theacid, they can be further modified by reaction with carbonyl groupreactive compounds, such as aldehydes, alcohols, etc. The4-ketooctanedioic acids can also be reduced chemically or catalyticallyto 1,4,8- octanetriols, which are also valuable intermediates forpolyesters.

As many apparently widely difierent embodiments of this invention may bemade without departing from the spirit and scope thereof, it to beunderstood that this invention is not limited to the specificembodiments thereof except as defined in the appended claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. Process for preparing 4-ketooctanedioic acids which comprisesreacting hydrogen, in an acidic medium having a pH less than 2 and incontact with a palladium catalyst, with a dilactone having the generalformula wherein one of the ring doubly bonded carbon atoms has its freevalence satisfied by R and the other of the ring doubly bonded carbonatoms has its free valence satisfied by R, said R and R being selectedfrom the class consisting of hydrogen, alkoxyaryl where the alkoxyradical is not more than 12 carbon atoms and the aryl radical ishydrocarbon of not more than 10 carbon atoms, haloaryl where the arylradical is hydrocarbon of not more than 10 carbon atoms, and monovalenthydrocarbon radicals, free from non-aromatic unsaturation, of not morethan 12 carbon atoms.

2. Process for preparing 4-ketooctanedioic acids as set forth in claim 1wherein said acidic medium having a pH less than 2 contains concentratedhydrochloric acid.

3. Process for preparing 4-ketosuberic acid which compriseshydrogenating, at a temperature of 20 to 40 C. under a hydrogen pressurewithin the range of atmospheric to 3000 lbs./ sq. in. and in contactwith a palladium catalyst in an acidic medium having a pH less than 2,the dilactone [A -bifuran]5,5'-dione.

4. Process for preparing 4-ketosuberic acid as set forth in claim 3whereby said acidic medium having a pH less than 2 contains concentratedhydrochloric acid.

5. Process for preparing 4-ketosuberic acid which compriseshydrogenating, at a temperature of 20 to 25 C. under a hydrogen pressurewithin the range of atmospheric to 1000 lbs./ sq. in. and in contactwith a palladiumon-charcoal catalyst in an acidic medium of acetic andhydrochloric acids having a pH less than 2, the dilactone [A-bifuranl-5,5-dione.

6. Process for preparing 4-ketosuberic acid which comprises reactinghydrogen, in an acidic medium having a pH less than 2 and in contactwith a palladium catalyst, with the dilactone having the formula I 7.Process for preparing 4-ketosuberic acid as set forth in claim 6 whereinsaid acidic medium having a pH less than 2 contains concentratedhydrochloric acid.

8. Process for preparing 4-ketosuberic acid as set forth in claim 6wherein said acidic medium having a pH less' Singleton .2.. Feb. 24,1948 Hagemeyer Oct. 11, 1949

1. PROCESS FOR PREPARING 4-KETOOCTANEDIOIC ACIDS WHICH COMPRISESREACTING HYDROGEN, IN AN ACIDIC MEDIUM HAVING A PH LESS THAN 2 AND INCONTACT WITH A PALLADIUM CATALYST, WITH A DILACTONE HAVING THE GENERALFORMULA